This application relates to optical switches, and more particularly, to optical switches for various optical devices and systems, including optical communication and networking devices and systems.
An optical switch may include a device to direct at least one optical beam from one direction of propagation to another direction of propagation. One or more such optical switches may be used in various optical communication modules or systems to route optical signal beams to their respective destinations. One exemplary application of optical switches is to reconfigure light paths to form new light paths when needed. In another example, such a switch may be used to perform protection switching in which, when a fiber link fails, the beam directed thereto is re-routed to a backup fiber link. Optical switching is important in optical WDM modules and systems since a single fiber link is used to simultaneously transmit optical carriers of different wavelengths to accommodate a large number of optical channels.
Multiple optical switches may be used to form a switching array to switch and direct an array of input optical beams to their respective outputs. Such an optical switching array may be designed to perform blocking switching and non-blocking switching. In a blocking switching array, when a first beam is directed to a selected output, another beam can be switched to only certain outputs and are blocked from reaching other outputs. In a non-blocking switching array, any input beam can be switched to reach any output. It is desirable to use non-blocking switching arrays to provide flexibility and versatility in directing optical beams in optical WDM communication systems and other optical systems that implement optical switching from multiple inputs to multiple outputs.
An optical switch according to one embodiment includes a switching element, an optical position sensor, and a control unit. The switching element is operable to direct an optical signal beam to one or more switching directions. The optical position sensor uses an optical servo beam to measure a property of the switching element to produce a position signal indicative of a deviation between an actual switching direction and a desired switching direction of the signal beam. The control unit is operable to respond to the position signal to control the switching element to reduce the deviation so that the signal beam can be substantially in the desired switching direction.
The optical switch may also include an optical terminal having an optical aperture to receive the signal beam directed from the switching element, and another optical position sensor coupled to the optical terminal to measure a position of the signal beam on the optical aperture to produce a second position signal. The switching element may be operable to respond to the second position signal to further control the actual switching direction of the signal beam so that the signal beam is directed to a desired position on the optical aperture.